Tessi “Snap Safe” E/P Cyl, 40/40 Chrome. The Tessi ‘Snap Safe’ cylinder has a built in weak spot (snap line) which is designed to break if the cylinder is forced. However, the lock will not fall apart as a result and, crucially, the door will remain locked. The owner of the house can still gain access with their key when they return. Each cylinder has been specially designed to be anti-pick, anti-bump, anti-drill and anti snap!